What to prescribe at the domain registrar so that mail works on the server?

Question

Mail server

Good day, please tell me what needs to be registered with the domain name registrar in order for my domain mail to work? (I set up a simple web server at home, based on the ISP manager). Unfortunately, the domain registrar does not have a personal account with settings, and you have to write to support. to change A records, etc. (alas, the support there is weak, and I myself have little understanding of this yet). DNSs have been updated, my domain is now assigned to my IP and is accessible from the world. I created a mailbox "[email protected]" and sent an email to myself on gmail, which I successfully received. But alas, the responses from gmail do not reach "[email protected]". I understand that the registrar needs to register MX records for the mail domain?
Please tell me, using an example, what needs to be specified at the domain registrar in order for mail to work normally.
And what would you recommend to read on this topic, for general information. Thanks in advance for your replies.
And is it enough to forward only the 25th port from the router to the server? or do you need another 110, 465, etc.?

Answer 1

Record Type - MX
Name - mx.domain.tld. (with a dot at the end or just mx and nothing else)
Value (@ or domain.tld. with a dot at the end)
This is if you just have the ability to receive letters, but without a DKIM signature, SPF records may not be accepted by the mail server, depending on how configured.
Port 25 needs to be opened so that mail servers can knock from outside and send mail. But this port may be closed by the ISP.